1. Field of Invention
The present invention relates to a method and a device for controlling ISG logic, and more particularly, to a method of controlling ISG (Idle Stop & Go) logic of an ISG vehicle which automatically stops the engine idling when the vehicle stops, and restarts the engine after a predetermined time to start the vehicle.
2. Description of Related Art
The gases causing the greenhouse effect of the various gases in the atmosphere are called greenhouse gases. As the greenhouse gases, there are carbon dioxide, methane, nitrous oxide, Freon gas, and ozone. Although vapor is the most responsible for causing the natural greenhouse effect, a representative greenhouse gas causing global warming is carbon dioxide.
Since the latter half of 20th century, global warming has rapidly progressed, unusual weather such that localized heavy rain, drought, typhoon etc. has been rapidly increased. If the present level of contamination continues, it is expected that the greenhouse gas emissions throughout the world will reach a level that seriously threatens mankind and the ecosystem in the sooner future.
Therefore, international cooperation for reducing amount of greenhouse gases has been established to cope with global warming due to the greenhouse gases.
Various efforts have been made to reduce the greenhouse gases in the transportation field, and as a part of the efforts, a great deal of effort is made in improving fuel efficiency.
At the present time where the fuel efficiency is a central theme, use of an ISG (Idle Stop & Go) system is increasing over the world.
The ISG system gives an order to stop an engine in idling, on the basis of information on vehicle speed, the revolution speed of an engine, and the temperature of cooling water etc.
In other words, the ISG system is an engine control system that is provided with a function that automatically stops the idling engine when a vehicle stops for waiting the traffic lights in a town, and restarts (goes) the engine when starting the vehicle after a predetermined time to make normal operation possible.
The ISG system is also called an idling stop control device. The ISG system can achieve fuel effect of about 5˜15% in the actual fuel efficiency mode.
A vehicle equipped with the ISG system is called an ISG vehicle, Although the highest prior object of the ISG is to improve the fuel efficiency, forbidden conditions may be set by inclination conditions and battery conditions in order to improve safety and commercial value of the vehicle system.
Referring to FIG. 1, FIG. 1 is a flowchart illustrating a general process of idle stop & go of a vehicle equipped with an automatic transmission.
A common vehicle with an automatic transmission should be equipped with a sub-oil pump to implement the ISG system and the sub-oil pump is used to keep the hydraulic pressure of the transmission when the engine stops.
In the vehicle provided with the ISG system by being equipped with the sub-oil pump, the engine is stopped (S130), when the brake pedal is pressed down to stop the vehicle at the D-range (“Yes” in S110) while an idle stop entrance condition is determined (S100). In this process, the sub-oil pump operates to keep the hydraulic pressure of the transmission.
That is, the condition for starting to stop the engine by the ISG system is that the vehicle stops with the vehicle speed not detected, the gear is held at the D-range, and the brake pedal is operated and kept at a predetermined time, in which the engine is stopped to increase the fuel efficiency.
Thereafter, when the brake pedal is released at the D-range, with the vehicle stopped (“Yes” in S150), the engine is automatically restarted (S170). In this state, the sub-oil pump is turned off.
That is, with the engine stopped by the ISG system, when the user's intention of starting the vehicle, such as releasing the brake pedal and operating the acceleration pedal, is detected, the engine is turned on to maintain normal traveling.
In the ISG vehicle described above, the logic controlling the ISG system should be changed for a level ground or an uphill, in order to keep the safety of the vehicle system, in accordance with the inclination of the road where the ISG vehicle is positioned now.
In particular, ISG logic control that can ensure stable start while preventing the vehicle from moving down for the movement characteristic of the vehicle, when restarting the vehicle, on a downhill.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.